The long-range objective of the proposed research is to understand the contribution of the activity of neurons in visual cortex to the visual behavior of animals and men. To approach this goal, human and animal psychophysical measures will be compared and correlated with electrophysiological measures and the effects of selective ablations of cat cortex evaluated. The proposed experiments are designed to link data derived from single cells in the cat visual cortex with related psychophysical data obtained from both humans and cats. Specific experiments are proposed which will: 1) Compare behavioral and electrophysiological estimates of contour orientation sensitivity in the cat; 2) Evaluate the contribution of several of the cortical visual areas to specific visual capacities in the cat using the ablation-behavior paradigm.